Connected Speech in Neurodegenerative Language Disorders: A Review

Abstract

Language assessment has a crucial role in the clinical diagnosis of several neurodegenerative diseases. The analysis of extended speech production is a precious source of information encompassing the phonetic, phonological, lexico-semantic, morpho-syntactic, and pragmatic levels of language organization. The knowledge about the distinctive linguistic variables identifying language deficits associated to different neurodegenerative diseases has progressively improved in the last years. However, the heterogeneity of such variables and of the way they are measured and classified limits any generalization and makes the comparison among studies difficult. Here we present an exhaustive review of the studies focusing on the linguistic variables derived from the analysis of connected speech samples, with the aim of characterizing the language disorders of the most prevalent neurodegenerative diseases, including primary progressive aphasia, Alzheimer's disease, movement disorders, and amyotrophic lateral sclerosis. A total of 61 studies have been included, considering only those reporting group analysis and comparisons with a group of healthy persons. This review first analyzes the differences in the tasks used to elicit connected speech, namely picture description, story narration, and interview, considering the possible different contributions to the assessment of different linguistic domains. This is followed by an analysis of the terminologies and of the methods of measurements of the variables, indicating the need for harmonization and standardization. The final section reviews the linguistic domains affected by each different neurodegenerative disease, indicating the variables most consistently impaired at each level and suggesting the key variables helping in the differential diagnosis among diseases. While a large amount of valuable information is already available, the review highlights the need of further work, including the development of automated methods, to take advantage of the richness of connected speech analysis for both research and clinical purposes.

Screening for Aphasia in NeuroDegeneration for the Diagnosis of Patients with Primary Progressive Aphasia: Clinical Validity and Psychometric Properties

“…Healthy individuals were expected to perform close to ceiling. In the case of MD, PD patients were expected to show normal or mildly affected language performance [10]. A similar prediction could be made for PSP patients, since those presenting with a clinical picture of nf/a-PPA were excluded.…”

Speech databases for mental disorders: A systematic review

“…Other picture description databases, referring to the cookie-theft stimuli, have also been introduced for broader speech samples. Boschi and colleagues29 gave a review on the tasks of picture description, story narration and interview, for finding out possible different contributions to the assessment of different linguistic domains. Images such as the picnic picture30 were used to develop a system that has 86.1% accuracy to predict early signs of cognitive decline; and the Picnic scene of Western Aphasia Battery31 or the tales of Cinderella , Snow White and the Seven Dwarfs and the Little Red Riding Hood 32 33 have also been used in various studies but to a much lesser extent.…”

Multilingual prediction of

“…Syntax and morphology also differ across languages, and the degree to which they are impaired in mild to moderate AD is unclear (Taler and Phillips, 2008). Pragmatic ability in AD may be disrupted (Chapman et al, 1998;Boschi et al, 2017); however, the CTP is not ideally suited for assessing pragmatics.…”